1. Field of Invention
The invention is directed to light emitters having layered semiconductor structures.
2. Description of Related Art
Light emitters with layered semiconductor structures, such as solid-state semiconductor lasers, are used as light sources for high-speed laser printing, optical fiber communications, data storage and other applications. One exemplary semiconductor laser is a so-called “edge emitting laser”, where light is emitted from the edge of the layered semiconductor structure. The light from the light emitters is usually emitted from specific defined regions, called ridge waveguides, of the structure. Such ridge waveguides form the lateral optical confinement structure and are typically small ridges of semiconductor material, with a generally flat upper surface and sloped sidewalls, that are created on top of the active semiconductor layer that emits light. A quantum well lies below the ridge waveguides. Light is generated in the quantum well by combining holes and electrons when the light emitter is driven. The quantum well is surrounded by cladding layers.
The semiconductor layers forming the light emitter are often formed using group III-V semiconductors. Many different group III-V semiconductor layers are stacked in turn to form the light emitter. Some of these layers are either p or n doped. Other ones of these layers are intrinsic, i.e., undoped. Many of the layers are multiple compound semiconductors that contain multiple group III cations and multiple group V anions. For example, group III cations include aluminum and gallium, while group V anions include arsenic and phosphorus. In many light emitters, the cladding layers and the waveguide layers includes phosphorous as part of the group V element. An example is disclosed in U.S. Pat. No. 6,502,399, which is incorporated herein by reference in its entirety.
When used in applications such as printing, optical fiber communications, data storage or the like, such phosphorous-containing semiconductor light emitters are often arranged in an array of multiple emitters. A multiple light emitter array shares a common bottom, or n-electrode and has separate, independently addressable, upper or p-electrodes.